That's a misleading way to put it. What it really undermines is the power of governments, regardless of the type. And that probably net promotes democracy, actually.
I agree with the second sentence but I don't see how history shows the third is true. Foreign interests have undermined both democratic and non-democratic states... any time a nation has taken control of its interests and resources (either democratically or not), powerful outsiders tend to put a stop to it. How does that promote democracy?
He argues that allowing people to move their money freely undermines democracy because the movement of money without the permission of the government restricts the ability of the government to set policy. He says that the people moving the money can "de-fund a country". This is the "two wolves and a sheep deciding what's for dinner" theory of democracy.
Chomsky is someone who I am really disappointed in. He is obviously very smart. He always seemed to me like the person with exactly the right mind for the tasks he set out to take on.
He seems to fall in to the same trap as the people who aren't.
Does this linguist really think higher interest rates will drive away capital in an open economy?